Metrics – a Java library which gives insight into what your code does

Developed by Yammer to instrument their JVM-based backend services, Metrics provides a powerful toolkit of ways to measure the behavior of critical components in your production environment.

With modules for common libraries like Guice, Jetty, Log4j, Apache HttpClient, Ehcache, Logback, Spring and reporting backends like Ganglia and Graphite, Metrics provides you with full-stack visibility.